fix: add mutex to gnmi lookup map (#11008)

(cherry picked from commit 72997ed)

plugins/inputs/gnmi/gnmi.go

@@ -57,7 +57,8 @@ type GNMI struct {
 	cancel          context.CancelFunc
 	wg              sync.WaitGroup
 	// Lookup/device+name/key/value
-	lookup map[string]map[string]map[string]interface{}
+	lookup      map[string]map[string]map[string]interface{}
+	lookupMutex sync.Mutex
 
 	Log telegraf.Logger
 }
@@ -88,7 +89,9 @@ func (c *GNMI) Start(acc telegraf.Accumulator) error {
 	var request *gnmiLib.SubscribeRequest
 	c.acc = acc
 	ctx, c.cancel = context.WithCancel(context.Background())
+	c.lookupMutex.Lock()
 	c.lookup = make(map[string]map[string]map[string]interface{})
+	c.lookupMutex.Unlock()
 
 	// Validate configuration
 	if request, err = c.newSubscribeRequest(); err != nil {
@@ -142,7 +145,9 @@ func (c *GNMI) Start(acc telegraf.Accumulator) error {
 
 		if subscription.TagOnly {
 			// Create the top-level lookup for this tag
+			c.lookupMutex.Lock()
 			c.lookup[name] = make(map[string]map[string]interface{})
+			c.lookupMutex.Unlock()
 		}
 	}
 	for alias, encodingPath := range c.Aliases {
@@ -310,6 +315,7 @@ func (c *GNMI) handleSubscribeResponseUpdate(address string, response *gnmiLib.S
 
 		// Update tag lookups and discard rest of update
 		subscriptionKey := tags["source"] + "/" + tags["name"]
+		c.lookupMutex.Lock()
 		if _, ok := c.lookup[name]; ok {
 			// We are subscribed to this, so add the fields to the lookup-table
 			if _, ok := c.lookup[name][subscriptionKey]; !ok {
@@ -318,6 +324,7 @@ func (c *GNMI) handleSubscribeResponseUpdate(address string, response *gnmiLib.S
 			for k, v := range fields {
 				c.lookup[name][subscriptionKey][path.Base(k)] = v
 			}
+			c.lookupMutex.Unlock()
 			// Do not process the data further as we only subscribed here for the lookup table
 			continue
 		}
@@ -330,6 +337,7 @@ func (c *GNMI) handleSubscribeResponseUpdate(address string, response *gnmiLib.S
 				}
 			}
 		}
+		c.lookupMutex.Unlock()
 
 		// Group metrics
 		for k, v := range fields {